(Modified from a report by Yvonne Sadovy, 2007)

Enhanced Monitoring of Grouper Spawning Aggregation at Ebill Channel -- Final Technical Report 


Several culturally and commercially important fishes aggregate to spawn in Palau at specific times and places and are, or were, targeted at such times and places. Some species are evidently more predictable than others in their times and places of spawning, and in most cases declines in catches have occurred over the last few decades. Many reasons were proposed for these declines and many of the fishers expressed concern that not enough was being done to protect the reef fish fishery of Palau. Although current laws are considered to be good and probably adequate, a major problem was perceived to be in their enforcement. The message was clear that more action is needed to ensure long-term sustainable use of reef fish resources, especially those that aggregate to spawn.

Many of the older fishermen, whether fishing for part of their lifetime full-time, or taking fish part-time for home use or for ‘Custom' had an extremely detailed recall of the species important to them. While this is not surprising, it is suggested that Palauan fishers are particularly knowledgeable. One fisher had maintained a written log of catches and moon phases when fish had eggs from his fishing days decades before, and others (divers) were able to describe in detail the different areas within specific grouper aggregation sites frequented by three different groupers species. Moreover, the information was generally consistent for particular species in terms spawning months, aggregation sites and trends in the fishery over time.

Interviewees were also generally knowledgeable about fishery regulations in effect in Palau, had considered reasons for changes in catches and sizes of fish over their fishing careers and were concerned about overfishing and other impacts. It was interesting to note that, while declines in grouper aggregations were often attributed to overfishing, declines in species that aggregate at inshore sites were more often attributed to pollution and increases in boat traffic. Most fishers noted substantial declines in certain aggregating species such as in mullets, milkfish, and also declines in landings from grouper, rabbitfish, unicornfish and red snapper aggregations. There were expressions of concern and recognition that more management is needed and that current regulations need to be better enforced. A number of fishers commented that reef fishes should be kept for ‘Custom' and home use only, and not traded commercially. It was considered that the regulations in place were good but that these were often not enforced.

The long-term declines strongly indicated by the interviews conducted are reason for concern. Given that actual fish numbers at several aggregations of groupers were estimated by underwater visual census to be hundreds or few thousands at any one time at an aggregation sites catches of a 0.5-1 ton of fish or more during a single fishing trip by one boat could represent a significant number of all the fish present (assuming an average of about 1 kg per fish) being removed before they have had a chance to spawn at any one site in any one month. Summed over many boats, months, years and sites, it is, perhaps, not surprising that marked declines in catches are indicated within a short period of time after sites are initially exploited. Even low levels of fishing pressure can clearly cause rapid and substantial declines if unchecked.

Monitoring species-specific catch rates over time is an essential part of understanding trends and conditions in a fishery and must be incorporated into any effective management regime. Unfortunately, this information is no longer collected on a regular basis in Palau, such that there is no means to establish the condition of the fishery from long-term catch or size trends, other than by one-off studies or fisher knowledge. This also means that it is difficult to assess the outcome of management interventions.

Management recommendations-

Some proposed management options with respect to Palauan situation includes: enforcement of regulations at night, especially with respect to grouper aggregation fishing, fishing on compressed air and poaching in northern areas of the country; strengthen fine for repeat offenders; extend existing law to protect grouper aggregations to include August; monitor landings of key reef fish resources, by species, on a regular and standardized basis; determine status of surgeonfishes, parrotfishes, snappers, and emperors; conduct education campaign to inform the public of the importance and relevance of laws that protect marine resources; prohibit export of all reef fishes; ban night fishing with spear; protect additional aggregating reef fishes from February to August inclusive; determine status of milkfish, bonefish and mullet stocks; include some reef channels and passes in marine protected areas; use reef fish resources principally for subsistence use and ‘Custom', with limited commercial exploitation; validate the aggregations reported in this study.